Hydraulic steering damper for motor vehicles

ABSTRACT

A hydraulic steering damper ( 9 ) is designed to be fitted inside a steering sleeve ( 3 ) between the steering sleeve ( 3 ) itself and a steering pin ( 2 ) that is coaxial with the sleeve ( 3 ) and having an axis of rotation (A). The damper ( 9 ) comprises a cylindrical lining ( 11 ), that can be fixed to the steering sleeve ( 3 ), and a cylindrical wall ( 13 ), that can be fixed to the steering pin ( 2 ). The lining ( 11 ) and the wall ( 13 ) form between them a gap ( 16 ) designed to hold a hydraulic fluid ( 17 ) and divided into a first and a second chamber ( 28, 29 ), which are in fluid communication with each other through a conduit ( 30 ). The damper ( 9 ) further comprises a blade ( 25 ) attached to the cylindrical wall ( 13 ) and designed to push the fluid ( 17 ) from one to the other of the chambers ( 28, 29 ) when the steering pin ( 2 ) is rotated relative to the steering sleeve ( 3 ).

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a steering damper, especiallyfor motor vehicles.

[0002] The steering mechanism of a motor vehicle usually has a dampingdevice used to smooth the steering action of the front wheel when thevehicle is travelling in order to improve road stability, and thusvehicle safety, especially at high speeds.

[0003] Conventional steering dampers, known in the jargon of the tradeas “steering brakes”, operate by friction on two matching parts thatrotate relative to each other.

[0004] In the past, dampers of this kind were mounted at the steeringheadstock and included a screw with which the rider of the vehicle, byusing a knob connected to the screw, could adjust the friction betweenthe parts that were rotating relative to each other. The adjustment wasperformed according to the number of road curves and the speed at whichthe vehicle was travelling.

[0005] These frictional dampers have two major disadvantages, namelyquick wear and the need to be continually adjusted by the rider. Theneed for continual adjustment may also give rise to hazardous situationsin that to adjust the damper, the rider loses concentration andtemporarily takes his/her mind off the road.

[0006] Subsequently, hydraulic dampers of linear type were developed.These consist of a tube and a stem, one connected to the frame and theother integral with the steering system.

[0007] These dampers, however, have the disadvantage of being bulky andnot easy to fit in with the other parts of the motor vehicle. They aretherefore built onto the vehicle like a separate add-on and usuallyhamper routine maintenance operations.

[0008] Another type of hydraulic damper taught by prior art is a damperbuilt into the steering headstock of a motor vehicle. This type ofdamper, although it overcomes the above mentioned disadvantages, bringsanother disadvantage in that the essential parts of it that ensure itscorrect operation are located between and act directly on the steeringheadstock and steering pin.

[0009] Thus, any maintenance on the steering headstock means alsocompletely dismantling the steering damper. This in turn requires thetime-consuming task of draining the hydraulic fluid.

SUMMARY OF THE INVENTION

[0010] The present invention therefore has for an object to overcome allthe disadvantages mentioned above by providing a steering damper that isat once functional, practical, economical and easy to construct.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The technical characteristics of the invention, with reference tothe above aims, are clearly described in the claims below and itsadvantages are apparent from the detailed description which follows,with reference to the accompanying drawings which illustrate a preferredembodiment of the invention provided merely by way of example withoutrestricting the scope of the inventive concept, and in which:

[0012]FIG. 1 is a schematic front view of a part of a motor vehicleequipped with the steering damper according to the present invention;

[0013]FIG. 2 is a section view from above of a detail from FIG. 1;

[0014]FIG. 3 is a section view from above of another embodiment of thedetail shown in FIG. 2.

[0015]FIG. 4 is a schematic front view of another embodiment of thedamper shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] With reference to FIG. 1, the numeral 1 denotes in its entiretythe zone of a motor vehicle where the steering is connected to thevehicle frame.

[0017] The connection zone 1 comprises a tubular steering pin 2 insertedcoaxially into a steering sleeve 3 that is integral with the abovementioned motor vehicle frame that is not illustrated.

[0018] The steering 2, whose axis of rotation is labeled A, is connectedat an upper end of it 4 to a steering headstock 5, and at a lower end ofit 6 to a bottom steering yoke 7.

[0019] The steering pin 2 can turn in the steering sleeve about the axisof rotation A.

[0020] The turning motion of the steering pin 2 within the steeringsleeve 3 is accomplished by conventional bearings 8, located close tothe upper and lower ends 4, 6 of the pin 2. These bearings areillustrated schematically in FIG. 1 and not further described.

[0021] The stems and tubes (not illustrated) of the telescopicsuspensions of the motor vehicle's front wheel are mounted on eitherside of the steering pin 2 and parallel to it on the steering headstock5 and bottom yoke 7.

[0022] The vehicle's steering gear (not illustrated) is usually mountedon the headstock 5 and acts on the above mentioned front wheel (notillustrated) in a customary manner and therefore not described in anydetail.

[0023] The connection zone 1 comprises a hydraulic steering damper 9positioned inside the steering sleeve 3.

[0024] With reference to FIG. 2, the steering damper 9 comprises anouter first portion 10 with a cylindrical lining 11 and an inner secondportion 12 with a cylindrical wall 13.

[0025] The cylindrical wall 13 and the cylindrical lining 11 are coaxialwith each other and with the steering pin 2.

[0026] The cylindrical wall 13 and the cylindrical lining 11 arerotatably connected to each other by two closing elements 14, 15,respectively upper and lower, having the shape of rings and designed toprovide a fluid-tight seal.

[0027] The cylindrical wall 13, cylindrical lining 11 and the twoclosing elements 14, 15 form a gap 16 which holds a hydraulic fluid 17.

[0028] With reference to FIG. 1, a lower end 13 a of the cylindricalwall 13 has formed on it a protrusion 18, extending outside the gap. Theprotrusion 18 engages a cross pin 19 in such a way as to lock thecylindrical wall 13 to the steering pin 2 to prevent relative rotationalor translational motion between the two parts.

[0029] The cross pin 19 passes through two coaxial through holes 20 madein diametrically opposite sides of the steering pin 2.

[0030] The cross pin 19 and the holes 20 made in the steering pin 2together constitute means 21 for fixing the cylindrical wall 13 to thesteering pin 2 itself.

[0031] Again with reference to FIG. 1, a pressure screw 22 is screwedinto a threaded hole 23 made in the steering sleeve 3 so as to stablyfix the cylindrical lining 11 to the steering sleeve 3 in a customarymanner which is not further described, thus preventing relativerotational or translational motion between the two parts.

[0032] The screw 22 and the hole 23 in the steering sleeve 3 togetherconstitute means 24 for fixing the cylindrical lining 11 to the steeringsleeve 3.

[0033] With reference to FIG. 2, the hydraulic steering damper 9 has ablade 25 fixed to the cylindrical wall 13 and extending radially fromthe wall 13 into the gap 16 and towards the cylindrical lining 11.

[0034] The extension of the blade 25 in axial direction (notillustrated) substantially coincides with the axial extension of the gap16.

[0035] The blade 25, actuated by the cylindrical wall 13 as it rotatesabout the axis A, constitutes means 26 for pushing the hydraulic fluid17 inside the gap 16.

[0036] The hydraulic steering damper 9 further comprises a dividingelement 27 attached to the cylindrical lining 11 and extending radiallyfrom the cylindrical lining 11 into the gap 16 and towards thecylindrical wall 3.

[0037] The dividing element 27 and blade 25 form, in the gap 16, a firstand a second chamber, labeled 28 and 29 respectively. The volume of eachof the chambers is variable but the sum of the two volumes is alwaysequivalent to the total working volume of the gap 16 that holds thefluid 17.

[0038] The dividing element 27 has a conduit 30 which places the firstand second chambers 28, 29 in fluid communication with each other.

[0039] The conduit 30 is acted upon by a throttle screw 31 for narrowingthe conduit 30 itself and which is screwed into a corresponding threadedthrough hole 32 made in the dividing element 27. An opening 33 made inthe steering sleeve 3 and in the cylindrical lining 11 provides accessto the throttle screw 31 from the outside of the steering sleeve 3.

[0040] The throttle screw 31 constitutes means 34 for adjusting thesection of the conduit 30 through which the fluid passes.

[0041] As illustrated in FIG. 3, the hydraulic damper 9 comprises aflexible element 35 for remotely operating on the throttle screw 31.

[0042] The flexible element 35 comprises a metal cable 36 attached, at afirst end of it 36 a, to the throttle screw 31 and, at a second end ofit 36 b, opposite the first end 36 a, to a hand-operated knob 37, whichcan be advantageously positioned on the steering gear (not illustrated)of the motor vehicle.

[0043] The flexible element 35 further comprises a removable sheath 38that covers the metal cable 36. The sheath 38 is fixed to acorresponding support 39 connected to the steering sleeve 3 close to theopening 33.

[0044] In another embodiment of the hydraulic damper 9 illustrated inFIG. 4, the means 21 for fixing the cylindrical wall 3 to the steeringpin 2 comprise a ring nut 40 having a tapered portion 41. The ring nut40 is designed to be screwed onto the protrusion 18 of the cylindricalwall 3 which has an upper threaded first end 42 and a lower taperedsecond end 43 shaped to match the tapered portion 41 of the ring nut 40.

[0045] The protrusion 18 has a plurality of axial slits 44 made in itscircular surface at equidistant angular intervals from each other, oneof the slits being schematically illustrated in FIG. 4 as a portionwithout hatching.

[0046] The operation of the hydraulic steering damper 9 will now bedescribed with reference to FIG. 1. After its components have beenassembled, the hydraulic damper 9 is placed over the steering pin 2, thelatter having previously been removed from the steering sleeve 3, andthen fixed to the steering pin 2 by inserting the cross pin 19 throughthe two coaxial holes 20 in the steering pin 2.

[0047] Therefore, the cross pin 19, besides constituting theaforementioned means 21 for fixing the cylindrical wall 3, also providesa sure and precise reference for locating the wall 13 relative to thesteering pin 2.

[0048] Once the cylindrical wall 3 of the hydraulic steering damper 9has been fixed to the steering pin 2, the pin 2 and the damper 9 areinserted together into the steering sleeve.

[0049] Starting from the configuration illustrated in FIG. 1, where thepre-assembled steering damper 9 is mounted inside the steering sleeve 3,any rotation of the steering pin 2 about its axis A causes the blade 25to push the fluid 17 through the conduit 30.

[0050] The passage of the hydraulic fluid 17 through the conduit 30produces the braking action of the steering damper 9 according to theknown principles of internal fluid friction.

[0051] Advantageously, the throttle screw 31 can be adjusted to vary theintensity of this braking action. Thus, screwing in the screw 31 reducesthe cross section of the conduit 30 for the passage of the fluid 17 and,vice versa, unscrewing the screw 31 increases the cross section for thepassage of the fluid 17.

[0052] In the embodiment illustrated in FIG. 3, the screw 31 is adjustedby turning the knob 37 which causes the metal cable 36 to be twistedrelative to the sheath 38.

[0053] Advantageously, every motor vehicle leaving the production andassembly line has the holes 20, 23 and the opening 33 made in it so thatthe pre-assembled steering damper 9 provided as an optional or standardaccessory can be quickly and easily fitted by any user.

[0054] In yet another embodiment which is not illustrated, the cross pin19 is a cotter pin designed to reduce or even eliminate any play that isproduced when the protrusion 18 is fixed to the steering pin 2.

[0055] The fixing illustrated in FIG. 4 is also designed to eliminateplay. Here, the ring nut 40 is screwed onto the matching upper threadedend 42 of the protrusion 18, the lower tapered end 43 of the protrusion18 having made in it one or more of the aforementioned axial slits 44.The axial slits 44 enable the protrusion 18 to be constricted, at leastat its lower tapered end 43, by the encircling pressure exerted on it bythe tapered portion 41 of the ring nut 40.

[0056] The invention described can be subject to numerous modificationsand variations without thereby departing from the scope of the inventiveconcept. Moreover, all the details of the invention may be substitutedby technically equivalent elements.

LIST OF REFERENCE NUMBERS

[0057]1 CONNECTION ZONE

[0058]2 STEERING PIN

[0059]3 STEERING SLEEVE

[0060]4 UPPER END OF PIN 2

[0061]5 STEERING HEADSTOCK

[0062]6 LOWER END OF PIN 2

[0063]7 BOTTOM STEERING YOKE

[0064]8 BEARINGS

[0065]9 HYDRAULIC DAMPER

[0066]10 OUTER FIRST PORTION OF 9

[0067]11 CYLINDRICAL LINING

[0068]12 INNER SECOND PORTION

[0069]13 CYLINDRICAL WALL

[0070]13 a LOWER END

[0071]14 UPPER CLOSING ELEMENT

[0072]15 LOWER CLOSING ELEMENT

[0073]16 GAP

[0074]17 HYDRAULIC FLUID

[0075]18 PROTRUSION

[0076]19 CROSS PIN

[0077]20 HOLES IN PIN 2

[0078]21 MEANS FOR FIXING THE WALL 13 TO THE PIN 2

[0079]22 PRESSURE SCREW

[0080]23 THREADED HOLE

[0081]24 MEANS FOR FIXING LINING 11 TO SLEEVE 3

[0082]25 BLADE

[0083]26 PUSHING MEANS

[0084]27 DIVIDING ELEMENT

[0085]28 FIRST CHAMBER

[0086]29 SECOND CHAMBER

[0087]30 CONDUIT

[0088]31 THROTTLE SCREW

[0089]32 THREADED HOLE

[0090]33 OPENING IN SLEEVE 3

[0091]34 MEANS FOR ADJUSTING CONDUIT 30

[0092]35 FLEXIBLE ELEMENT

[0093]36 METAL CABLE

[0094]36 a FIRST END OF CABLE 36

[0095]36 b SECOND END OF CABLE 36

[0096]37 KNOB

[0097]38 SHEATH

[0098]39 SUPPORT FOR 38

[0099]40 RING NUT

[0100]41 TAPERED PORTION OF RING NUT 40

[0101]42 UPPER THREADED FIRST END OF PROTRUSION 18

[0102]43 LOWER TAPERED SECOND END OF PROTRUSION 18

[0103]44 AXIAL SLITS IN PROTRUSION 18

What is claimed is:
 1. A hydraulic steering damper for a motor vehiclehaving a frame comprising a steering sleeve (3), a steering pin (2)inserted coaxially into the steering sleeve (3) and connected at anupper end of it (4) to a steering headstock (5), and at a lower end ofit (6) to a bottom steering yoke (7), the steering pin (2) being able toturn within the steering sleeve (3) about an axis of rotation (A),wherein the hydraulic steering damper (9) is pre-assembled and ready tobe fitted inside the steering sleeve (3) between the sleeve (3) itselfand the steering pin (2).
 2. The damper according to claim 1, comprisingat least an outer first portion (10) that can be fixed to the steeringsleeve (3) and an inner second portion (12) that can be fixed to thesteering pin (2), the first and second portions (10, 12) forming betweenthem at least a gap (16) to hold a hydraulic fluid (17), the gap (16)having at least a first and a second chamber (28, 29) which are in fluidcommunication with each other through a conduit (30) made in a dividingelement (27) that is integral with the outer first portion (10).
 3. Thedamper according to claim ², comprising means (26) for pushing the fluid(17) so as to transfer the fluid (17) from the first chamber (28) to thesecond chamber (29) and vice versa through the conduit (30).
 4. Thedamper according to claim 1, comprising means (34) for adjusting thecross section of the conduit (30) for the passage of the fluid (17). 5.The damper according to claim 4, wherein the adjustment means (34) areremotely operated.
 6. A hydraulic steering damper for a motor vehiclehaving a frame comprising a steering sleeve (3), a steering pin (2)inserted coaxially into the steering sleeve (3) and connected at anupper end of it (4) to a steering headstock (5), and at a lower end ofit (6) to a bottom steering yoke (7), the steering pin (2) being able toturn within the steering sleeve (3) about an axis of rotation (A), thehydraulic steering damper (9) being pre-assembled and ready to be fittedinside the steering sleeve (3) between the sleeve (3) itself and thesteering pin (2) and comprising at least an outer first portion (10)that can be fixed to the steering sleeve (3) and an inner second portion(12) that can be fixed to the steering pin (2), the first and secondportions (10, 12) forming between them at least a gap (16) to hold ahydraulic fluid (17), the gap (16) having at least a first and a secondchamber (28, 29) which are in fluid communication with each otherthrough a conduit (30) made in a dividing element (27) that is integralwith the outer first portion (10), wherein the outer first portion (10)includes a cylindrical lining (11), the lining (11) being designed to beplaced inside the steering sleeve (3) coaxially with the sleeve (3)itself.
 7. The damper according to claim 6, comprising means (24) forfixing the lining (11) to the steering sleeve (3).
 8. The damperaccording to claim 6, wherein the inner second portion (12) comprises acylindrical wall (13), the cylindrical wall (13) being designed to befitted coaxially on the steering pin (2), over the outside surface ofthe pin (2).
 9. The damper according to claim 8, characterised in thatit comprises means (21) for fixing the cylindrical wall (13) to thesteering pin (2).
 10. The damper according to claim 6, comprising means(34) for adjusting the cross section of the conduit (30) for the passageof the fluid (17).
 11. The damper according to claim 10, wherein theadjustment means (34) are remotely operated.